CUET · PHYSICS · PYQ PAPER 2025
If light of wavelength 412.5 nm is incident on each of the metals given below, which ones will show photoelectric emission ?
| Metal | Work Function (eV) |
| Na | 1.92 |
| K | 2.15 |
| Ca | 3.20 |
| Mo | 4.17 |
Choose the correct answer from the options given below:
- A Na and K only
- B Ca and Mo only
- C Na, K and Ca only
- D K, Ca and Mo
Answer & Solution
Correct Answer
(A) Na and K only
Step-by-step Solution
Detailed explanation
\(E = \frac{hc}{\lambda}\) \(E = \frac{1240}{\lambda \text{ (nm)}}\) \(E = \frac{1240}{412.5} \approx 3.006 \text{ eV}\) For photoelectric emission, \(E \geq \phi\). Na: \(3.006 \text{ eV} \geq 1.92 \text{ eV}\) (Yes) K: \(3.006 \text{ eV} \geq 2.15 \text{ eV}\) (Yes) Ca:…
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